Jaw-locking mechanism for pipe wrenches



Sept. 21, 1954 E. M. CHAPPELL. JR 2,689,496

JAW-LOCKING MECHANISM FOR PIPE WRENCHES Filed May 25, 1953 FIG.I

zlNVENTgiia Patented Sept. 21, 1954 UNITED STATES PATENT OFFICE JAW-LOGKING MECHANISM FOR PIPE WRENCHES Edward M. Chappell, Jr., Dana Point, Calif. Application May 25, 1953, Serial No. 357,219 1 Claim. (01. 81-100) This invention relates to pipe wrenches and more particularly to mechanism for releasing, holding, and adjustin the movable jaw of a pipe wrench.

It is characteristic of pipe wrenches that they are designed to rock with a ratchet action about a cylindrical object such as a, pipe, increasing the tightness of their grip upon such an object when moved rotatively in one direction and relaxing their grip when moved in the opposite direction. To accomplish this purpose, pipe wrenches have one jaw which is not only movable longitudinally relatively to the other law but also has limited angular movement relatively to the other jaw, the angl between the opposed jaw faces changing very slightly as the angle between the jaw shanks changes. Relative angular movement of the jaw shanks is usually provided for by having the guide passage or sleeve through which one shank slide pivoted to the handle or otherwise enabled to tilt. It is an object of this invention to provide a pipe wrench which may be set for any desired jaw-spread without the use of worm-screws to move it.

A further object of my invention is to provide a pipe wrench which may be closed to a desired jaw-spread by simply pushing one jaw relatively to the other in a closing direction, and which then will remain at the set spread-with allowance .for the previously mentioned ratchet action-until it is intentionally released, and which then may be released by finger-pressure on a simple locking device.

Still another object of my invention is to provide a pipe wrench having a locking device which itself receives very little strain but which effects a look by binding, one upon another, parts of the wrench which are necessarily strong for the purposes of the wrench and which can therefore undergo the locking strain without injury.

In the accompanying drawing, illustrative of a typical embodiment of my invention, Fig. 1 is a side view of my improved p'pe-wrench, showing the wrench clamped and locked;

Fig; 2 is a fragmentary view from the opposite side, ShOWillg the wrench unlocked;

Fig. 3 is an elevational view, drawn on an enlarged scale, of a locking plate used in my wrench; and

Fig. 4 is a perspective view, drawn on an enlarged scale, of a spring for actuating the locking plate.

Having reference to the details of the drawing, I have shown a Wrench having a handle 5, and a jaw 6 integral with the handle and generally referred to as the fixed jaw of such a wrench because it has no movement relative to the handle. A sleeve 1, also integral with the handle 5, has a passage 8 for slidingly receiving the shank 9 of a movable L-shaped jaw 19, the serrated jawface II of the jaw 10 bein opposed to the serrated jaw-face 12 on the end of the jaw 6 in planes substantially normal to the handle 5. It will be seen that the sleeve 1 is not pivoted upon the handle 5 in the manner of the well-known Stillson wrench, but permits rocking movement of the jaw Ill by virtu of having the passage 8 tapered in the direction of angular movement of the jaw 1!] so as to closely embrace the shank 9 at the end of the passage 8 distant from jaw face l2, and being expanded at the end of the passage 8 adjacent the jaw-face I 2. It will seem that the jaw tends to rock upon the shoulders l3 and M at the margins of the narrower end of the passage 8.

The sleeve 1 also has a transverse opening or passage [5 which extends into the jaw 6 and intersects the passage 8. The passage l5 communicates with the outer surface! 6 of the sleeve 1 through an opening IT. The wall It of the passage [5 remote from the jaw-face l2 and the wall I9 of the opening I! in continuation thereof are in alignment normal to the passage 8; the opposite wall 20 of the passage I5 is inclined so that the passage I5 widens as it enters the jaw 6, the wall 20 joining the wall 2| of the opening I! at a position slightly inwardly from the opening H but outwardly from the passage 8. The wall 2| is normal to the passage 8, like its opposite wall I 9, and consequently there is formed at the junction of the walls 20 and 2| a shoulder 22, on the side of the passage [5 nearest the jaws 6 and 10.

A plurality of plates 25, shown individually in Fig. 3 and contained as a group in the passage [5 have stems 26 which extend through the opening I! and apertures 21 arranged to be aligned with the passage 8 and to receive the shank 9 of the jaw [0. The apertures 21 are of suificient size in the longitudinal direction of the plates 25 to permit the shank 9 to slide freely through them when the plates are normal to the shank as shown in Fig. 2, but to cause the plates to bind upon the shank when slightly inclined at acut angles to the shank as shown in Fig. 1. A leaf spring 28, having openings 29 to receive the shank 9, is mounted behind the plates 25 and urges them to assume the inclined position shown in Fig. 1.

A sufficient number of plates 25 are used so that in combination with the spring 28 they substantially fill the opening ll. One plate of requisite thickness may be used in place of the group of plates.

The shank 9 of the jaw in may be provided with a stud 3! which by contact with the sleeve 1 prevents the jaw ID from being entirely removed from the sleeve.

It will now be seen that the effect of the leaf spring 28 is to cause the plates 25 to pivot tilt upon the shoulder 22 and that forward pressure, towards the jaws of the wrench, upon the stems 26 will cause the plates 25 to assume the position normal to the shank 9 illustrated in Fig. 2, the spring 28 being then compressed, and that release of such pressure permits the spring to move the plates pivotally upon the shoulder 22 to the acute angle position relative to the shank 9. In the position shown in Fig. 2, the jaw H! may be moved freely in either longitudinal direction, the shank 9 sliding through the passage 8 and through the apertures 21 of the plates 25. But in their inclined position the plates 25 bind with light pressur upon the shank 9 and tend to pivot the jaw Ill upon the marginal shoulder I3, causing the shank 9 to frictionally engage the wall of the passage 8 remote from the jaw 6. In these circumstances the jaw 10 may be moved longitudinally only with great difficulty.

When the jaw faces II and I2 engage an object such as indicated at 3|, and the handle 5 is swung as usual in the direction of the arrow S, torque is applied to cause the jaw H] to move in the direction of the arrow T relatively to the jaw 6, this movement tightening the jaws upon the object 3|. The same movement of course tends to pivot the shank 9 upon the shoulder 13 towards the jaw 5. This pivotal movement of the shank 9 tends to increase the relative inclination of the shank 9 and plates 25, but this inclination is already at the permitted maximum. The plates will slide upon th spring 28 and on the fulcrum shoulder 22, to follow the shank 9, but will bind ever more tightly upon the shank 9 and increase the pressure of the shank against the passage margin [4.

The jaw ill is now held firmly against longitudinal movement but will relax its grip upon the object 3! the instant that torque upon the handle 5 is reversed.

To release the wrench entirely from the object 7 31, the stems 26 are pushed toward the wrench head to bring the plates 25 normal to the shank 9.

Practically no torque or bending strain is applied to the plates 25, the strain upon them being largely longitudinal, and such bending strain as occurs takes place at the area in contact with the fulcrum shoulder 22 where the plates have the greatest unbroken width and strength between the stems 26 and the apertures 21. The forces which hold the jaw ID are appliedthrough the plates 25 in small part to the fulcrum shoulder 22 and in large part first to the shoulder l3 at the narrow end of the passage 8 and then to the opposite shoulder H3. The further the jaw I0 is extended relatively to the jaw 6and then, not infrequently, the greater power is required to turn a larger objectthe greater the binding pressure upon the shoulder Hi becomes, the object 3| then becoming the moving force, the shoulder l4 being the fulcrum, and the resistance of the plates 25 to longitudinal extension of the apertures 21 being the resistance of a leverage system.

Iclaim:

A wrench comprising: a fixed jaw; a handle integral with said fixed jaw; a movable jaw; said jaws having jaw faces opposed in planes substantially normal to said handle; a shank on said 1 movable jaw substantially normal to the jawface thereof; a sleeve on said fixed jaw having a first passage for slidingly engaging said shank; said passage having marginal shoulders closely embracing said shank at the end of said passage distant from said jaws and being expanded at its opposite end to permit rocking movement of said shank within said passage upon said marginal shoulders as fulcrums; said sleeve having a second passage intersecting said first passage and having a shoulder within said second passage disposed outwardly from said first passage and on the side of said second passag toward said jaws; a plate contained in said second passage having an aperture aligned with said first passage through which said shank may slide when said plate lies perpendicular to a longitudinal axis of said shank and being tiltable about said last mentioned shoulder to lie at an angle with respect to said axis of said shank so that margins of said aperture bind upon said shank, the angle of tilt increasin when said shank is.rocked so as to bring said jaws closer together; and means resiliently urging said plate to assume said tilted angle.

References Cited in the file of this patent UNITED STATES PATENTS 

